Needle looms typically employ a pair of spaced connecting rods to reciprocate a needle beam with respect to a web of non-woven fabric being needled by the loom. The connecting rods are journaled at one of their ends on an eccentric cam or on a crank arm carried by a drive shaft in the loom, and are journaled at the other of their ends to an upper surface of the needle beam. Guide arrangements, including guide posts fixedly carried by the needle beam and slide bushings fixedly carried by the frame of the needle loom and in engagement with the guide posts, are generally employed to confine the reciprocating motion of the needle beam to rectilinear reciprocating motion. Examples of the foregoing prior art types of needle beam guide systems for needle looms may be found in the following patents: U.S Pat. No. 3,216,082, dated Nov. 9, 1965, to R. S. Goy; U.S. Pat. No. 3,602,967, dated Sept. 7, 1971, to Zocher et al; U.S. Pat. No. 3,798,717, dated Mar. 26, 1974, to R. E. Brochetti; and, U.S. Pat. No. 3,889,326, dated June 17, 1975, to T. Tyas.
During operation of a needle loom, the needles of the reciprocating needle beam penetrate the non-woven web that is being needled. Since the needles are densely mounted on the needle boards, significant forces are generated by the penetration of the needles into the web, which forces are resisted by the needle beam. These forces cause the needle beam to deflect slightly between and beyond the positions at which the connecting rods are mounted on the needle beam, resulting in a gull-wing-like curvature of the needle beam. Since the guide posts of the guide system which confines the reciprocating motion of the needle beam to rectilinear motion are mounted on the needle beam, either between the connecting rods or outside the connecting rods, an angular displacement of the guide posts occurs due to the deflection of the beam under load. This displacement is due to the fact that the guide posts remain perpendicular to the surface of the beam and, consequently, they lean toward their associated connecting rods and skew in their associated guide bushings.
This skewing action causes very heavy loads to occur on both the guide posts and the guide bushings of the guide system, creating excessive heat and requiring some form of lubricant to keep the heat generated under control. Since lubricants depend on seals to be contained, the prior systems have only been as good as the sealing arrangements employed to contain the lubricants in the guide bushings. However, these arrangements have been far from satisfactory, allowing contamination of the needled web due to lubricant leaking after only a relatively short service life. Moreover, since prior art forms of needle beam guide systems have involved the reciprocation of relatively massive guide posts in connection with maintaining rectilinear motion of the needle beams, the needling speeds that have been achievable in the past have been limited.
It is, therefore, a primary object of the present invention to provide an improved needle beam guide system in which the slide bushings are pivotally mounted to their supports in order to allow them to remain aligned with the guide posts under all operating conditions of the needle beam.
Another object of the present invention is to fix the guide posts of the guide system to the frame of the needle loom and to mount the guide bushings of the guide system on the reciprocating needle beam in order to reduce the mass that has to be moved during reciprocation of the needle beam.
Yet another object of the present invention is to resiliently mount the guide bushings inside the bushing housings so as to allow small movements to occur therebetween in order to absorb shock and some of the misalignment inherent in the operation of needle beams.
Further objects and advantages of this invention will become apparent as the following description proceeds.